Static Dental Disparity and Morphological Turnover in Sharks across the End-Cretaceous Mass Extinction
The Cretaceous–Palaeogene (K–Pg) mass extinction profoundly altered vertebrate ecosystems and prompted the radiation of many extant clades [1, 2]. Sharks (Selachimorpha) were one of the few larger-bodied marine predators that survived the K–Pg event and are represented by an almost-continuous dental...
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| Published in: | Current biology 2018-08, Vol.28 (16), p.2607-2615.e3 |
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| Main Authors: | , , , , |
| Format: | Article |
| Language: | eng |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | The Cretaceous–Palaeogene (K–Pg) mass extinction profoundly altered vertebrate ecosystems and prompted the radiation of many extant clades [1, 2]. Sharks (Selachimorpha) were one of the few larger-bodied marine predators that survived the K–Pg event and are represented by an almost-continuous dental fossil record. However, the precise dynamics of their transition through this interval remain uncertain [3]. Here, we apply 2D geometric morphometrics to reconstruct global and regional dental morphospace variation among Lamniformes (Mackerel sharks) and Carcharhiniformes (Ground sharks). These clades are prevalent predators in today’s oceans, and were geographically widespread during the late Cretaceous–early Palaeogene. Our results reveal a decoupling of morphological disparity and taxonomic richness. Indeed, shark disparity was nearly static across the K–Pg extinction, in contrast to abrupt declines among other higher-trophic-level marine predators [4, 5]. Nevertheless, specific patterns indicate that an asymmetric extinction occurred among lamniforms possessing low-crowned/triangular teeth and that a subsequent proliferation of carcharhiniforms with similar tooth morphologies took place during the early Paleocene. This compositional shift in post-Mesozoic shark lineages hints at a profound and persistent K–Pg signature evident in the heterogeneity of modern shark communities. Moreover, such wholesale lineage turnover coincided with the loss of many cephalopod [6] and pelagic amniote [5] groups, as well as the explosive radiation of middle trophic-level teleost fishes [1]. We hypothesize that a combination of prey availability and post-extinction trophic cascades favored extant shark antecedents and laid the foundation for their extensive diversification later in the Cenozoic [7–10].
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•Shark teeth reveal morphological turnover during the end-Cretaceous mass extinction•Fossil shark dental disparity is decoupled from taxonomic richness•Cretaceous–Palaeogene shark disparity was nearly static unlike other marine predators•Prey availability and trophic cascades may have initiated Cenozoic shark radiations
Bazzi et al. analyze shark tooth morphology to reconstruct global faunal turnover across the end-Cretaceous mass extinction. Stable disparity, selective extinctions and trophic restructuring collectively favored modern lineage radiations. The composition of living shark communities is thus underpinned by extinction recovery 66 million years ago. |
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| ISSN: | 0960-9822 1879-0445 1879-0445 |